This invention relates to valves and more particularly to a valve configuration for use with retail gasoline pumps for avoiding or minimizing product loss when a filter element is changed.
The usual filter which is used to filter gasoline flowing out of a service station pump to an automobile gas tank or other container is similar to those commonly used for filtering motor oil in an engine and includes a flange with internal threads which screw on a threaded post or boss which includes an outlet passage. The flange is permanently attached to a cylindrical can or container which contains a filter member. A series of ports in the flange communicate with a source of gasoline under pressure which then flows across the filter and out the outlet passage to a meter unit and then to the hose. Such filter elements need to be replaced at intervals of one to several months depending on the volume of gasoline flowing through the pump and possible sources of contamination.
Each time the filter is changed, a large amount (usually more than a gallon) of product is lost to the ground or to the air. This is because the filter is usually mounted horizontally to the meter unit and when the filter is removed, the pressure in the line, metering unit and filter forces the product to flow out of the filter and onto the ground.
Current state and federal air and water regulations state that this product (gasoline or diesel fuel) must be contained and must not escape to the air or soil. There are currently no valves available in the industry which enable a service station operator to comply with these regulations.